Added line-break constraint

js/semantics/Calculus.lisp

@@ -3072,9 +3072,11 @@
   (preprocess-grammar-or-lexer preprocessor-state :grammar kind2 name start-symbol))
 
 
-(defun generate-no-line-break-constraint (terminal)
+(defun generate-line-break-constraints (terminal)
   (assert-type terminal user-terminal)
-  (list (list (make-lf-terminal terminal) :no-line-break)))
+  (list 
+   (list terminal :line-break)
+   (list (make-lf-terminal terminal) :no-line-break)))
 
 
 ; (line-grammar <name> <kind> <start-symbol>)
@@ -3087,8 +3089,8 @@
 (defun preprocess-line-grammar (preprocessor-state command name kind2 start-symbol)
   (declare (ignore command))
   (preprocess-grammar-or-lexer preprocessor-state :grammar kind2 name start-symbol
-                               :variant-constraint-names '(:no-line-break)
-                               :variant-generator #'generate-no-line-break-constraint))
+                               :variant-constraint-names '(:line-break :no-line-break)
+                               :variant-generator #'generate-line-break-constraints))
 
 
 ; (lexer <name> <kind> <start-symbol> <charclasses-source> <lexer-actions-source>)

js/semantics/Grammar.lisp

@@ -1225,7 +1225,7 @@
 ;
 ; A variant-generator is either nil or a function that takes a terminal and outputs a list of its variants.
 ; Each variant is specified as a cons of:
-;   A variant terminal
+;   A variant terminal (may be eql to the original terminal; this lets one add constraints that exclude the original terminal)
 ;   A list of names of variant constraints which exclude this variant terminal
 ;
 ; The rhs can also contain lookahead constraints of the form
@@ -1317,8 +1317,9 @@
       (dolist (terminal (hash-table-keys terminals-hash))
         (dolist (variant-and-constraints (funcall variant-generator terminal))
           (let ((variant (first variant-and-constraints)))
-            (push variant (gethash terminal terminal-variants))
-            (setf (gethash variant terminals-hash) t)
+            (unless (grammar-symbol-= terminal variant)
+              (push variant (gethash terminal terminal-variants))
+              (setf (gethash variant terminals-hash) t))
             (dolist (constraint (rest variant-and-constraints))
               (push variant (cdr (assoc constraint variant-constraint-forbid-lists))))))))
     

js/semantics/HTML.lisp

@@ -487,6 +487,7 @@
     ((:but-not 6) (b "except"))
     ((:begin-negative-lookahead 13) "[lookahead" :not-member-10 "{")
     ((:end-negative-lookahead 2) "}]")
+    ((:line-break 12) "[line" nbsp "break]")
     ((:no-line-break 15) "[no" nbsp "line" nbsp "break]")
     (:subscript sub)
     (:superscript sup)

js/semantics/RTF.lisp

@@ -323,6 +323,7 @@
     ((:but-not 6) (b "except"))
     ((:begin-negative-lookahead 13) "[lookahead" :not-member-10 "{")
     ((:end-negative-lookahead 2) "}]")
+    ((:line-break 12) "[line" ~ "break]")
     ((:no-line-break 15) "[no" ~ "line" ~ "break]")
     (:subscript sub)
     (:superscript super)

js2/semantics/Calculus.lisp

@@ -3072,9 +3072,11 @@
   (preprocess-grammar-or-lexer preprocessor-state :grammar kind2 name start-symbol))
 
 
-(defun generate-no-line-break-constraint (terminal)
+(defun generate-line-break-constraints (terminal)
   (assert-type terminal user-terminal)
-  (list (list (make-lf-terminal terminal) :no-line-break)))
+  (list 
+   (list terminal :line-break)
+   (list (make-lf-terminal terminal) :no-line-break)))
 
 
 ; (line-grammar <name> <kind> <start-symbol>)
@@ -3087,8 +3089,8 @@
 (defun preprocess-line-grammar (preprocessor-state command name kind2 start-symbol)
   (declare (ignore command))
   (preprocess-grammar-or-lexer preprocessor-state :grammar kind2 name start-symbol
-                               :variant-constraint-names '(:no-line-break)
-                               :variant-generator #'generate-no-line-break-constraint))
+                               :variant-constraint-names '(:line-break :no-line-break)
+                               :variant-generator #'generate-line-break-constraints))
 
 
 ; (lexer <name> <kind> <start-symbol> <charclasses-source> <lexer-actions-source>)

js2/semantics/Grammar.lisp

@@ -1225,7 +1225,7 @@
 ;
 ; A variant-generator is either nil or a function that takes a terminal and outputs a list of its variants.
 ; Each variant is specified as a cons of:
-;   A variant terminal
+;   A variant terminal (may be eql to the original terminal; this lets one add constraints that exclude the original terminal)
 ;   A list of names of variant constraints which exclude this variant terminal
 ;
 ; The rhs can also contain lookahead constraints of the form
@@ -1317,8 +1317,9 @@
       (dolist (terminal (hash-table-keys terminals-hash))
         (dolist (variant-and-constraints (funcall variant-generator terminal))
           (let ((variant (first variant-and-constraints)))
-            (push variant (gethash terminal terminal-variants))
-            (setf (gethash variant terminals-hash) t)
+            (unless (grammar-symbol-= terminal variant)
+              (push variant (gethash terminal terminal-variants))
+              (setf (gethash variant terminals-hash) t))
             (dolist (constraint (rest variant-and-constraints))
               (push variant (cdr (assoc constraint variant-constraint-forbid-lists))))))))
     

js2/semantics/HTML.lisp

@@ -487,6 +487,7 @@
     ((:but-not 6) (b "except"))
     ((:begin-negative-lookahead 13) "[lookahead" :not-member-10 "{")
     ((:end-negative-lookahead 2) "}]")
+    ((:line-break 12) "[line" nbsp "break]")
     ((:no-line-break 15) "[no" nbsp "line" nbsp "break]")
     (:subscript sub)
     (:superscript sup)

js2/semantics/RTF.lisp

@@ -323,6 +323,7 @@
     ((:but-not 6) (b "except"))
     ((:begin-negative-lookahead 13) "[lookahead" :not-member-10 "{")
     ((:end-negative-lookahead 2) "}]")
+    ((:line-break 12) "[line" ~ "break]")
     ((:no-line-break 15) "[no" ~ "line" ~ "break]")
     (:subscript sub)
     (:superscript super)